It looks like mechanical damage, scarring from being injured.

Like Gabby said - an injury of some type and the plant has scabbed over leaving a scar. Remove any leaves that you find objectionable. The plant will put on new leaves.

I moved my P. micans to a large mail tray (with a hole drilled in for drainage) many years ago. This particular philodendron is very sensitive to cold compared to all the other philodendrons (since I saw this many years ago, I try to bring in philodendrons before all the other houseplants in fall). Anyway it always puts out new growth each and every year. I don't give it much care other than water when needed and the annual move outdoors for summer and back indoors for winter.

Here it is with a couple other philodendrons I threw in the same tray this winter.

One year I had it in a coir lined basket (2010) and can't remember why I abandoned that idea. Maybe the golden pothos took over.